Dumbbell Hammer Curls
Stand with your feet shoulder-width apart and a dumbbell in each hand, arms by your sides and thumbs pointing forward. Keeping this grip, curl both dumbbells up together as far as you can, pause briefly at the top and lower slowly. Your hands stay in the same position the whole time.
This exercise trains your elbow flexors in the hammer grip: the biceps, brachialis and brachioradialis bend the elbow together. Your hands stay in the same position throughout, so there is just one movement to learn: curl up and lower.
All you need is two dumbbells, and it pairs well with Dumbbell Rotation Curls, where your hands turn as you curl.
From the studio: For me, this is the technically simplest arm exercise there is. That is what I see in the studio.
Starting position
Stand with your feet shoulder-width apart and a dumbbell in each hand. Let your arms hang by your sides with your palms facing your body and your thumbs pointing forward: this is the hammer grip. Keep your stomach and lower back lightly braced.
Now curl both dumbbells up together, powerfully and as far as you can. Your hands stay in the hammer grip, so at the top your thumbs point towards your shoulders. Near the top, your upper arms come slightly forward.
Pause briefly at the top. Then lower slowly until your arms hang straight by your sides again.
The three cues
- Hammer grip — thumbs pointing forward
- Curl up powerfully as far as you can, pause at the top
- Lower slowly
Common faults
| Fault | How to fix it |
|---|---|
| You throw the dumbbells up with momentum | The weight is too heavy. Go lighter and only add weight once every rep is clean at the same tempo. |
| Your hands turn as you curl | Keep your thumbs pointing forward and up the whole time, so you stay in the hammer grip. |
| You let the dumbbells drop on the way down | Lower slowly until your arms are straight again. |
| You only curl partway | Curl as far as you can and pause briefly at the top. |
Variations
| Variation | When to use it |
|---|---|
| Light dumbbells | Curl up powerfully, pause at the top, lower slowly. Move on when every rep moves at the same steady tempo, without swinging. |
| Full range, hammer grip | From straight arms up as far as you can, pause at the top, lower slowly, with your hands in the hammer grip throughout. |
| Heavier dumbbells | Once technique and tempo stay clean on every rep, add weight in small steps. |
Reps and load
Go for around 10 to 15 reps with a weight that keeps every rep at the same tempo, without swinging. Only add weight once that holds for every rep.
The exercise fits well at the end of an upper-body session, for example alongside Dumbbell Rotation Curls.
Which muscles do the work
| Muscle | Role | What it does here |
|---|---|---|
| Biceps, long head M. biceps brachii, caput longum | Prime mover | Bends the elbow |
| Biceps, short head M. biceps brachii, caput breve | Prime mover | Bends the elbow |
| Brachialis M. brachialis | Prime mover | Lies beneath the biceps and bends the elbow whatever the hand position |
| Brachioradialis M. brachioradialis | Synergist | Runs along the thumb side of the forearm and helps bend the elbow |
| Front delts M. deltoideus, pars clavicularis | Synergist | Steady the shoulder and lift the upper arm slightly forward at the top |
| Forearms Mm. antebrachii | Stabiliser | Grip the dumbbells and keep the wrists straight in the hammer grip |
| Core M. rectus abdominis, M. erector spinae | Stabiliser | Keeps the upper body upright and still |
The biceps, brachialis and brachioradialis bend your elbow together, and all three work in the hammer grip. Your front delts lift the upper arm slightly forward at the top, while your forearms and core keep your wrists and upper body steady.
Explained in full
Andreas shows the hammer grip, the powerful curl and slow lowering, explains when to add weight, and shows which muscles do the work. · 0:50
Seeing it done right is not the same as doing it right
Video, cues and variations take you a long way. What they cannot give you is an outside eye at the moment the movement isn't quite there yet. That is what training with me is for — in the studio or in a workshop.
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Sources
Coratella G, Tornatore G, Longo S, Toninelli N, Padovan R, Esposito F, Cè E. (2023). Biceps brachii and brachioradialis excitation in biceps curl exercise: different handgrips, different synergy. Sports (Basel) 11(3):64. DOI: 10.3390/sports11030064 — Measures muscle activity in 10 competitive bodybuilders during two-arm curls (8-RM load, 6 reps) with a supinated, neutral (hammer) and pronated grip. On the way up, biceps activity was higher with the supinated grip than the hammer grip (+12%), and the brachioradialis was slightly higher too (+6%); the front delts were higher with the hammer grip (+9%). The basis for saying all three elbow flexors work in the hammer grip and for listing the front delts as a synergist. It does not support the idea that the hammer grip especially targets the brachioradialis. A very small, highly trained sample. There is no measurement specific to the Academy's target group (aged 40 to 60, training two to four hours a week). (Evidence type: EMG)
Kleiber T, Kunz L, Disselhorst-Klug C. (2015). Muscular coordination of biceps brachii and brachioradialis in elbow flexion with respect to hand position. Front Physiol 6:215. DOI: 10.3389/fphys.2015.00215 — Measures the biceps and brachioradialis in 16 healthy people during slow elbow flexion with a pronated, neutral and supinated forearm. Biceps activity did not differ significantly between hand positions; the brachioradialis differed only between pronated and the other two. The basis for the page not attributing a single-muscle focus to the hammer grip. A small sample, very slow movement, age not given in the abstract. (Evidence type: EMG)
Boland MR, Spigelman T, Uhl TL. (2008). The function of brachioradialis. J Hand Surg Am 33(10):1853–1859. DOI: 10.1016/j.jhsa.2008.07.019 — Uses fine-wire electrodes in 10 people (9 men, 1 woman, aged 34 ± 10) to measure the brachioradialis during elbow flexion in three forearm positions with 0 to 67 N. Activity did not differ between positions (23 ± 5% of maximum when bending, 11 ± 5% when lowering). The basis for saying the brachioradialis helps bend the elbow in every hand position. A small sample and light loads; the closest in age to the target group. (Evidence type: EMG)
Caufriez B, Dugailly PM, Brassinne E, Schuind F. (2018). The role of the muscle brachioradialis in elbow flexion: an electromyographic study. J Hand Surg Asian Pac Vol 23(1):102–110. DOI: 10.1142/S2424835518500145 — Measures the biceps, brachialis and brachioradialis in 15 young healthy men during isokinetic elbow flexion in three forearm positions. All three were very active in every position, with the brachioradialis slightly higher with the forearm supinated. The basis for listing the brachialis and brachioradialis as prime movers. Surface EMG over the brachialis (crosstalk possible), maximal effort. (Evidence type: EMG)
Naito A, Sun YJ, Yajima M, Fukamachi H, Ushikoshi K. (1998). Electromyographic study of the elbow flexors and extensors in a motion of forearm pronation/supination while maintaining elbow flexion in humans. Tohoku J Exp Med 186(4):267–277. DOI: 10.1620/tjem.186.267 — Measures the biceps, brachialis, brachioradialis and triceps in 9 healthy people while the forearm rotates with the elbow held bent. The biceps was more active with the forearm supinated, the brachialis and brachioradialis the more the forearm was pronated. The basis for saying the three elbow flexors share the work depending on hand position. Not a curl, neutral not analysed separately, a very small sample. (Evidence type: EMG)
Augustin F, Piñero A, Enes A, et al. (2025). Do cheaters prosper? Effect of externally supplied momentum during resistance training on measures of upper body muscle hypertrophy. Int J Exerc Sci 18(3):329–342. DOI: 10.70252/GDBL2230 — An 8-week study in 30 young adults: one arm did biceps curls and triceps extensions strictly, the other with momentum (4 sets of 8–12 reps to failure, twice a week). Muscle thickness and arm circumference increased similarly in both. So the page justifies working without swinging by control over the movement and the weight, not by more muscle growth. (Evidence type: Intervention study)
Schoenfeld BJ, Ogborn DI, Krieger JW. (2015). Effect of repetition duration during resistance training on muscle hypertrophy: a systematic review and meta-analysis. Sports Med 45(4):577–585. DOI: 10.1007/s40279-015-0304-0 — A meta-analysis of 8 studies: muscle growth was similar with repetition durations from 0.5 to 8 seconds, and very slow reps over 10 seconds are probably less effective. The basis for treating the tempo (powerful up, slow down) as a technique and control cue, not a promise of more growth. (Evidence type: Meta-analysis)
Weisgarber KD, Candow DG, Farthing JP. (2015). Whey protein and high-volume resistance training in postmenopausal women. J Nutr Health Aging 19(5):511–517. DOI: 10.1007/s12603-015-0454-7 — A 10-week study in 12 postmenopausal women (aged 57 ± 4.7) including biceps curls, 3 sets at 30% of maximal strength to fatigue, twice a week. Biceps curl strength and elbow flexor thickness increased significantly (P = .006 and P = .022). The basis for saying that elbow flexor training works at the age of the target group. A very small, female-only sample, grip and implement not stated in the abstract. (Evidence type: Intervention study)
A note on context: EMG studies show which muscles an exercise recruits — that is a good reason to pick it, but it does not replace adjusting things to the person in front of you. See a doctor for persistent or severe pain.